 
   These handlers take two arguments;  `coeffects` and `event`, and they return `effects`.
 
-  (fn [coeffects event]
-     {:db ...
-      :dispatch ...})
+      (fn [coeffects event]
+         {:db ...
+          :dispatch ...})
 
    Wrap handler in an interceptor so it can be added to (the RHS) of a chain:
      1. extracts `:coeffects`

  "Returns an interceptor which wraps the kind of event handler given to `reg-event-ctx`.
  These advanced handlers take one argument: `context` and they return a modified `context`.
  Example:
     (fn [context]
        (enqueue context [more interceptors]))"
  [handler-fn]
  (->interceptor
    :id     :ctx-handler


  Usage:

      (defn my-f
        [a-val b-val]
        ... some computation on a and b in here)

      (on-changes my-f [:c]  [:a] [:b])

  Put this Interceptor on the right handlers (ones which might change :a or :b).
  It will:
